Improvement in spirit-levels



FRANK W. MARSTON, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO JOAB MORSS,OF SAME PLACE.

IMPROVEMENT IN SPIRIT-LEVELS.

Specification forming part of Letters Patent No. 1&09055, dated June 17,1873 g application iiled March 5, 1873.

Llo all whom it may concern:

Be it known that I, FRANK W. MAns'roN, in the city and county ofPhiladelphia, State of Pennsylvania, have invented an Improved SpiritLevel, of which thefollowing is a specitication:

The objects of my invention are, first, to insure the permanency ot therelative position, at right angles to each other, ofthe two tubes of aspirit-level; second, to afford facilities for the ready adjustment ofthe said tubes; and, third, to determine the exact inclination from ahorizontal or vertical plane of any object to which the level isapplied.

I attain the first of these objects by vconfining at right angles toeach other, and to one and the same frame B, shown in Figure 1 of theaccompanying drawing, the two glass tubes AD and D 5 and the secondobject I attain by hinging the said frame to the block A, andbycombining the frame with a controllingserew, a, as shown in thedrawing 5 and the third object I attain by a graduated scale, b,arranged to be adjustable in guides at the end of the block, as shown inFig. 3 of the drawing. A recess is formed in the block for the receptionof the frame B, which is provided with the projections or trunnions e,adapted to bcarin gs in the said block. At the end of the long arm ofthe frame B is a projection, j', having an opening threaded internallyand adapted to the thread of the setscrew h, which is contined between aplate in the block and the usual plate t', through the elongated openingin which the bubble in the tube D may be observed.

By introducing an appropriate implement through an opening in the platei this setscrew may be readily turned, and the frame B may be thereby soadjusted that its tubes shall exactly accord with the under face of theblock. It should be understood that the two tubes D and D are properlyadjusted in the frame B, exactly at right angles to each other beforethe said frame is applied to the block 5 hence in subsequent adjustmentsof the frame in the block it is not necessary to regard more than one ofthe tubes, as the proper adjustment of one tube in respect to the blockmust be simultaneous with that of the other.

The duty of the adjustable scale in determining the exact extent of thedeparture-from a vertical or horizontal plane (see Fig. 2) of any objectto which the level may be applied, will be readily understood Withoutexplanation.

I claim as my inventionl. A spirit-level in which the two tubes areadjusted at right angles to each other in the same frame, separable fromthe block, as and for the purpose set forth. Y

' The tubes D D', secured at right angles to each other to a frame, B,and simultaneously' adjustable by a screw, h, as set fort-h.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

FRANK W. MARSTON.

-W'itnesses P. F. BROWN, Lnwrs G. GARR.

